Controlling residual hydrogen gas in mass spectra during pulsed laser atom probe tomography


Residual hydrogen (H 2 ) gas in the analysis chamber of an atom probe instrument limits the ability to measure H concentration in metals and alloys. Measuring H concentration would permit quantification of important physical phenomena, such as hydrogen embrittlement, corrosion, hydrogen trapping, and grain boundary segregation.

Increased insight into the behavior of residual H 2 gas on the specimen tip surface in atom probe instruments could help reduce these limitations. The influence of user-selected experimental parameters on the field adsorption and desorption of residual H 2 gas on nominally pure copper (Cu) was studied during ultraviolet pulsed laser atom probe tomography.

The results indicate that the total residual hydrogen concentration, H TOT , in the mass spectra exhibits a generally decreasing trend with increasing laser pulse energy and increasing laser pulse frequency. Second-order interaction effects are also important.

The pulse energy has the greatest influence on the quantity H TOT , which is consistently less than 0.1 at.% at a value of 80 pJ.



Published on: 2017-02-23

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